While it is mainly used for beverages, coffee is the focus of substantial cultivation and production. According to June 2006 figures of the United States Department of Agriculture, the world's coffee production is 16.34 billion pounds per year. That amount is currently increasing.
Raw coffee beans contain about 20 wt % triglycerides. There have been some reports of attempts to obtain biofuel, such as biodiesel, from low quality coffee beans. However, it appears that these attempts are using traditional methods to process the whole, green coffee beans. Such methods can suffer from a number of disadvantages.
Biofuels from raw crops are typically produced by mechanically pressing the source material to extract triglycerides. The triglycerides are then hydrolyzed to produce fatty acids. The fatty acids are then esterified, typically using lower alcohols such, as methanol or ethanol.
Mechanical extraction can produce limited yields of triglycerides, particularly when the source material is large or coarse. In addition, mechanical extraction can also extract impurities, which can reduce the quality of the resulting biofuel or require purification steps, which can increase the cost of producing the biodiesel or reduce the overall yield.
Typical biofuels can suffer from a number of disadvantages. For example, many biofuels are not stable, such as being stable for less than 24 hours. This lack of stability may limit adoption of biofuels due to concerns about engine fouling or storage container fouling by degraded fuel. Distribution also may be an issue with unstable fuels, as they may not be transportable, or transported only short distances, before they degrade.
Attempts have been made to stabilize biofuels by adding various additives to the biofuel. For example, some studies have attempted to extend the time before the biodiesel degrades by incorporating various additives into the fuel, such as synthetic phenolic antioxidants. However, many biofuels with such additives are still only stable for about 30 days or less. Additive addition also may increase the cost of the fuel, making it less attractive compared with conventional petroleum-based fuels, or create other concerns, such for engine performance or emissions.